Makindo Medical Notes

Related Subjects: |AF - General |AF and Anticoagulation |AF and Rate Control |AF and Rhythm Control and Cardioversion |AF ECG |DC cardioversion

Caution: haemodynamic compromise purely from AF is uncommon. More often the driver is the underlying illness (sepsis/pneumonia, AMI, PE, decompensated LV failure, metabolic derangement). Treat the precipitant first; if uncertain that AF is the primary problem, get senior input.

About

• All unstable tachyarrhythmias are indications for synchronised DC cardioversion (DCCV).
• If AF and unstable/compromised → DCCV now. Start therapeutic anticoagulation as soon as feasible.
• Compromise (Resus Council life-threatening features): shock (SBP <90), syncope, myocardial ischaemia (angina), or acute heart failure/pulmonary oedema.
• Synchronisation times the shock to the R wave to avoid the T wave (prevents R-on-T → VF).

Emergency DCCV – Indications

• Any tachyarrhythmia with life-threatening features.
• Fast AF with hypotension/ischaemia/pulmonary oedema (often HR >150/min) despite initial measures.
• SVT/atrial flutter with compromise when vagals/adenosine (SVT) or rate control have failed.
• AF with pre-excitation (WPW physiology) and fast ventricular response.
• VT with a pulse causing compromise.

Elective DCCV – Indications

• AF as part of a rhythm-control strategy (symptoms, heart failure, first episode, younger patients).
• Atrial flutter (often highly responsive to low-energy DCCV).
• Ensure adequate anticoagulation strategy (see below) or a TOE-guided approach.

When Elective DCCV is Unlikely to Succeed / Defer

• Long-standing persistent AF (>12 months) or markedly enlarged LA (e.g., >5.0 cm / high LA volume).
• Reversible causes not corrected (infection, thyrotoxicosis, alcohol binge, pericarditis, uncontrolled mitral valve disease).
• Prior failed cardioversion despite antiarrhythmics.
• Not adequately anticoagulated (unless TOE strategy planned).

Anticoagulation Around Cardioversion

• Elective: If AF >24–48 h or of unknown duration, give therapeutic OAC for ≥3 weeks before and ≥4 weeks after DCCV (warfarin with INR 2–3 or a DOAC). TOE-guided early cardioversion is an alternative if no LA/LAA thrombus is seen.
• Emergency: If AF >48 h and not anticoagulated, DCCV may still be lifesaving—proceed for instability, then give formal OAC for ≥4 weeks. Consider TOE if time allows.
• Beyond 4 weeks, continue long-term OAC according to CHA₂DS₂-VASc risk, not rhythm status.

Procedure – Key Steps

• Senior review; discuss with cardiology if time allows; obtain consent where possible.
• Sedation (anaesthetics support recommended) with full monitoring and airway readiness.
• Pad position: antero-posterior (or antero-lateral) with firm pressure; shave if very hairy; good gel contact.
• Synchronise to the R wave for each shock; ensure nobody is touching the patient or equipment; keep supplemental O₂ away from the spark zone.
• Typical initial energies (biphasic):
  • Narrow regular (SVT/typical flutter): 50–100 J
  • Narrow irregular (AF): 120–200 J (escalate as needed)
  • Wide regular (VT with pulse): 100 J (escalate)
  • Wide irregular: defibrillate (unsynchronised)
• If unsuccessful: up to 3 shocks, then give amiodarone 300 mg IV over 10–20 min, continue with infusion (e.g., 900 mg over 24 h), and repeat DCCV.
• Admit to a monitored bed; address triggers; plan ongoing rate/rhythm strategy and OAC.

Complications (Risk-benefit)

• Stroke: <1% if appropriately anticoagulated—hence the peri-DCCV OAC rules.
• Post-shock bradycardia/pause (usually transient; have atropine/pacing capability available).
• Superficial skin burns/myalgia at pad sites; rare sedation-related events.

Investigations

• ECG (12-lead), FBC, U&E, Mg²⁺, TFTs, CRP, CXR (if indicated), INR (if on VKA).
• TOE if AF >48 h and not pre-anticoagulated, when early DCCV is planned.

Images

References

• Resuscitation Council UK. Adult tachycardia (with pulse) algorithm, 2021. (Energy ranges, step-up strategy).
• NICE NG196: Atrial fibrillation: diagnosis and management (and BNF treatment summary). (DOAC first-line; peri-cardioversion OAC).
• ESC 2020 AF guideline. (≥3 weeks pre- and ≥4 weeks post-DCCV, TOE-guided early cardioversion, ≥4 weeks post-DCCV if AF >24 h).